Table 2.
Bland-Altman statistics and non-parametric comparisons by Wilcoxon signed rank test
| Comparison | Sample size | Degree of freedom | Individual agreement | Average agreement | Wilcoxon signed rank test | |||
|---|---|---|---|---|---|---|---|---|
| Mean of difference (d) with (95% CI) | SD of difference | Upper LoA d + 1.96SD |
Lower LoA d-1.96SD |
SE | ||||
| NDI-10 vs. NDI-8 | 201 | 200 | −2.3* (−3.0 - -1.6) | 5.0 | 7.4 | −12.0 | 0.4 | P < 0.001* |
| NDI-10 vs. NDI-5 | 201 | 200 | −4.6* (−5.3 - -3.8) | 5.3 | 5.8 | −14.9 | 0.5 | P < 0.001* |
| NDI-8 vs. NDI-5 | 201 | 200 | −2.3* (−2.7 - -1.9) | 2.8 | 3.3 | −7.8 | 0.2 | P < 0.001* |
* significant as p < 0.001
NDI-10: The total score of NDI 10-item (original) version on ordinal scale with maximum of 50 points
NDI-8: The total score of NDI 8-item version on linear scale with maximum of 50 points
NDI-5: The total score of NDI 5-item version on linear scale with maximum of 50 points
SD standard deviation
SE standard error base on the mean of difference